The preferred embodiment concerns a cooling device and a cooling method for a printing substrate in an electrographic printer or copier.
Workflow printer or copiers are known (see for example WO 98/39691 A1). In such a printer or copier, charge images of the images to be printed are generated on a charge image carrier (for example a photoconductor belt). The charge image carrier is subsequently moved past developer stations, respectively once per color. For example, these transport developer comprised of toner and carrier to the charge image carrier. The toner migrates onto the charge image carrier corresponding to the charge images and inks these. The toner images are transfer-printed onto a printing substrate in the next step and are fixed on this. The precise workflow of the printing method can be learned from WO 98/39691 A1, the content of which is herewith incorporated into the disclosure.
A thermofixing is normally used to fix toner images onto the printing substrate. For example, fixing rollers (of which at least one is heated) are used for this, or infrared radiators are used as a heat source. The thermofixing of the toner images on the printing substrate requires that the printing substrate still exhibit a temperature of, for example, 120° C. or higher upon leaving the fixing station, such that a further processing of the printing substrate is difficult. In order to remedy this disadvantage, it is known to cool the printing substrate after the fixing station.
According to DE 42 35 667 C1, cooled air is blown onto the printing substrate to cool the printing substrate. The cooling device used for this possesses cooling surfaces provided with openings. Cold air is supplied to the openings via an air guide channel, flows out from the openings below the printing substrate and there forms a cooling air cushion. Air is simultaneously blown onto the other side of the printing substrate, and in fact counter to the travel direction of the printing substrate.
Additional cooling devices are known from, for example: DE 38 38 021 C2; EP 0 758 766 B1; DE 201 19 854 U1; U.S. Pat. Nos. 6,907,220 B2; 6,567,629 B2. For example, there aerators are used to cool a printing substrate, or externally or internally cooled rollers.